Fluidized bed reactor with vertical cooling coils

Abstract

A fluidized bed reactor is provided with heat exchange coils for controlling the temperature of the fluidized bed, with only vertically oriented sections of the coils exposed to the erosive conditions in the fluidized bed. The vapor-liquid circuit, of which the heat exchanger coils are a part, is arranged to operate on the principle of natural circulation. At least some of the tuyere elements discharge fluidizing gas at a level substantially above the constriction plate and the bed solids below the level of the tuyere gas discharge constitute a static layer during fluidization in which the lower angle bends of the heat exchange coils are embedded and so shielded from erosion by the fluidized solids of the bed proper. The static layer of bed solids also accommodates thermal expansion of the lower angle bend due to elevated temperatures and insulates the constriction plate from the high temperatures in the reactor. The upper angle bends of the heat exchange coils are located above the fluidized solids of the bed in the freeboard of the reactor. A plurality of the heat exchange coils may be fixed in removable hatches or panels provided in the wall of the reactor so that the heat exchange coils may be readily withdrawn from the reactor for maintenance purposes.